The death of the radical American cleric Anwar Awlaki is a major intelligence coup for the U.S. Another American citizen, an Al Qaeda propagandist, was also killed in the attack.

Reporting from Washington and Cairo — U.S. Predator drone aircraft armed with Hellfire missiles carried out the targeted killing in northern Yemen of Anwar Awlaki, a radical Muslim cleric who was a U.S. citizen, and also killed another American who produced virulent propaganda for Al Qaeda.

The lethal strike, a CIA-led covert operation that relied on U.S. special operations forces and Yemeni authorities, marks the first time since in the anti-terrorism campaign began after the Sept. 11 attacks a decade ago that the U.S. government deliberately tracked and killed an American citizen.

Officials said Yemeni authorities had interrogated an Al Qaeda operative in their custody, and he had disclosed Awlaki's hideout at a house in the town of Khashef, in Yemen's northern Jawf province. The house was placed under surveillance, which lasted for several weeks.

When the convoy drove away from the hideout Friday morning, a pair of Predator drones flying overhead tracked their movement. At least one missile was fired at about 10 a.m., and local reports said the bodies were so mangled that they were buried in sandbags.

U.S. officials said the surveillance and drone attack was code-named Operation Troy. A U.S. Navy amphibious landing ship steamed offshore, the officials said, with Harrier jets prepared to attack the convoy if the Predators failed. The jets were not used.

Although Awlaki was a mid-level figure in Al Qaeda, he cast a potent shadow in U.S. counter-terrorism circles because he spoke fluent English and was effective at reaching disaffected Muslims in the United States and elsewhere via speeches and sermons on the Internet.

His death thus marks not only an escalation of Obama administration efforts to kill leaders of Al Qaeda and its affiliates, but another significant intelligence coup after the CIA-led raid that killed Osama bin Laden on May 2 in Pakistan.

Unlike that raid, U.S. officials were not eager to provide details of the operation against Awlaki, possibly fearing that disclosures about U.S. operations in Yemen could jeopardize future operations.

Awlaki, who was known for his fiery sermons on the Internet and on YouTube urging Muslims to attack the United States, was put on a CIA list of militants to be killed or captured after an Obama administration review last year concluded he played an operational role in Al Qaeda in the Arabian Peninsula. The group that has carried out numerous terrorist plots against U.S. targets.

Friday's drone strike also killed Samir Khan, who grew up in New York and ran a pro-Al Qaeda web site in Charlotte, N.C., before he moved to Yemen several years ago. Khan is believed to have founded and edited Inspire, a glossy English-language magazine published in Yemen that praised suicide bombers and methods of mass murder.

Politicians from both parties in Washington applauded the death of the two influential Al Qaeda figures. But the strike also intensified a debate about whether, by killing American citizens without due process or judicial review, the U.S. government had crossed into dangerous legal territory with no clear limits.

U.S. counter-terrorism officials said they did not know in advance that Khan was riding in the convoy with Alwaki. They identified him only after U.S. and Yemeni personnel who rushed to the scene recovered fingerprints from the victims' remains.

"Samir Khan was a bonus. It was a two-fer," said Rep. Mike McCaul (R-Texas), who serves on the House committee on homeland security. "It's a pretty good hit."

Two unidentified passengers in the vehicles were also killed, officials said.

In remarks at Fort Myer, Virginia, President Obama stressed the direct role that Awlaki allegedly played in planning and directing terror plots against Americans.

Obama thus offered a glimpse into the government's analysis into why it was legal to kill a U.S. citizen, which remains secret.

Obama called Awlaki "the leader of external operations" for the Al Qaeda affiliate in Yemen, and said he "directed" both the failed attempt to blow up a Northwest Airlines passenger jet over Detroit on Christmas Day in 2009, and a plan to detonate explosives hidden in printer cartidges aboard U.S. cargo planes in 2010.

"And he repeatedly called on individuals in the United States and around the globe to kill innocent men, women and children to advance a murderous agenda," Obama said.

U.S. forces fired a missile at a convoy in which Awlaki was believed to be a passenger in May, but he escaped.

The only other U.S. citizen known to have been killed by the CIA in a targeted strike was Ahmed Hijazi, who was in a car destroyed in a Predator strike in 2002. But the target was a different passenger, and the CIA did not learn Hijazi was killed until afterward.

Pardiss Kebriaei, staff attorney at Center for Constitutional Rights in New York, a liberal public interest law firm, challenged the legality of Awlaki's killing.